1. Field of the Invention
The present invention relates to a method of cathodically electrocoating electroconductive articles. More particularly, this invention relates to cathodically electrocoating an electroconductive article with the simultaneous decomposition of the counter ion.
2. Brief Description of the Prior Art
Cationic electrodeposition is practiced on an industrial scale and involves immersing an electroconductive article in an aqueous dispersion of a polymeric material which contains cationic groups such as quaternary ammonium salt groups or amine salt groups. An electric current is passed through the dispersion between a metallic article as cathode and a counter electrode as anode to cause a deposition of material on the cathode. During the electrodeposition, acid is generated at the counter electrode and continuously builds up in the bath where it can corrode equipment and raise the conductivity of the bath making it more difficult to electrodeposit smooth uniform coatings.
The art has recommended numerous ways to control this acid build-up such as by subjecting the bath to ultrafiltration and electrodialysis. However, these methods have shortcomings associated with them and they require additional equipment costs as well as the expense of monitoring and maintaining the additional equipment.